General procedure for the synthesis of 3,4,5-trifluoro-1,2-diaminobenzene from 2,3,4-trifluoro-6-nitroaniline: Concentrated hydrochloric acid (15 mL) was slowly added dropwise to a mixture containing 2,3,4-trifluoro-6-nitroaniline (12 mmol) and tin powder (30 mmol). The reaction mixture was heated to reflux for 1.5 hours and subsequently cooled to room temperature. The reaction mixture was neutralized with 50% sodium hydroxide solution to pH 9-10. the precipitate was collected by filtration, dried and extracted with hot ethyl acetate (80 mL). After evaporation of the filtrate, 3,4,5-trifluoro-1,2-phenylenediamine (product 10) and possible by-products were obtained. 3,4,5-trifluoro-1,2-phenylenediamine (10) was obtained in a yield of 1.40 g (70% yield); brown crystals in appearance; melting point of 85-87 °C; and thin layer chromatography (TLC) Rf value of 0.72.
